Field of the Invention
This invention relates in general to medical equipment and procedures. In particular, the invention relates to catheters for use in performing certain medical procedures, such as the treatment of brain arteriovenous malformations includes endovascular embolization, surgical resection, and stereotactic radiotherapy, alone or in combination.
The present invention is a tool to more safely and more effectively implement endovascular treatment of arteriovenous malformations and arteriovenous fistulas, reducing procedural times and exposure to X-ray radiation to the patient and the treating staff.
Background Art
Treatment of brain arteriovenous malformations includes endovascular embolization, surgical resection, and stereotactic radiotherapy, alone or in combination. In the past, n-butyl cyanoacrylate (nBCA) was used as an adjunct to surgery; however, introduction of a dimethyl sulfoxide (DMSO)-based embolic agent, Onyx (ev3, Covidien), and more recently in other countries, PHIL™ (Precipitating Hydrophobic Injectable Liquid, MicroVention® Terumo) and SquidPERI (EVOH, by emboflu, Switzerland), and advancement in micro-catheter design often offered better endovascular results in brain arteriovenous malformations treatment. Liquid embolic agents are the preferred embolic material in endovascular treatment of pial and brain arteriovenous malformations and dural arteriovenous fistulas. Advancements in micro-catheter design and emergence of new embolic agents offer better results in endovascular treatment of brain arteriovenous malformations.
Among said advances is the use of dual lumen devices which employ one lumen to dispense a balloon to block Onyx flow and a second lumen to deploy Onyx. Said prior art teaches that double-lumen versions are more efficient than single-lumens because double-lumen allow simultaneous execution of tasks.
The reduction from two lumens (note: for medical devices, a luminous term referring to the channel within a tube) to one is non-obvious. In particular, the prior art related to lumens teaches that double-lumen versions are more effective single-lumens for managing unexpected as well as anticipated difficulties. Additionally, the prior art related to lumens teaches that double-lumen versions are more efficient than single-lumens because double-lumen allow simultaneous execution of tasks. Thus, the prior art teaches away from reducing lumens generally and specially teaches away from single-lumens.
The prior art contains several catheters with a hole in addition to the end hole. Most of these are taught by twelve patents: U.S. Pat. No. 9,440,043 (Arora et al.); U.S. Pat. Nos. 9,399,112; 9,364,634; 8,496,629; 8,403,911; 6,223,637; 5,954,687; 5,800,407; 5,180,387; 4,970,926; 4,784,638; and 4,755,176.
However, most are designed to drain cerebrospinal fluid from the ventricular through a catheter that enters through a hole in the skull and would not be capable of injecting glue into an artery that enters through the femoral artery and is snaked up through blood vessels in the body. Additionally, the inventions described in said patents could be used to inject something directly into the brain and/or ventricle. However, they could not be used to inject something into an artery within the brain, or to provide a temporary arterial bypass. If it were introduced directly into the artery through the brain it would undoubtedly cause a life threatening bleed in the brain. The medical basis is that a catheter designed to be inserted directly into the brain has no possible role for an intravascular application.
Additionally, the structure of the devices taught by said twelve patent differs from the structure of the present invention. In particular, U.S. Pat. No. 9,440,043, which is a catheter having a tapered structure and balloon formed above a lower drainage hole differ from the present invention because it has a balloon which covers the distal end hole and the present invention does not. U.S. Pat. No. 9,399,112 is a catheter hole having an inclined trailing edge while the present invention does not have an angled side hole. U.S. Pat. No. 9,364,634 teaches an embedded co-extrusion for improving catheter hole array efficiency, whereas the present invention does not use co-extrusions. U.S. Pat. No. 8,496,629 is a catheter which uses staggered diffusion holes a flow breaking feature, the present invention does not require any flow breaking feature. Similarly, U.S. Pat. No.8,403,911 uses diffusion side holes to improve catheter efficiency, while the present invention does not require any flow breaking feature, including diffusion side holes. U.S. Pat. No. 6,223,637 is a catheter side-wall hole cutting apparatus, whereas the present invention while capable of deploying a device to cut a catheter side-wall has neither a suction element nor a cutting element. U.S. Pat. No. 5,954,687 teach the use of a fluid reservoir, however the present inventions does not. U.S. Pat. No. 5,800,407 is a multiple hole epidural catheter which teaches the use of both permanently opened and permanently closed holes, whereas the present inventions uses holes which can be both opened and closed on a temporary basis in addition to holes which are permanently open. Furthermore, the present invention is designed for intravascular, not epidural use. U.S. Pat. No. 5,180,387 teaches the use of angled holes in a catheter with a non-circular bore, the present invention teaches non-angled holes in a circular bore.
U.S. Pat. No. 4,970,926 teaches an apparatus for making angled hole ventricular catheter which uses a plurality of rods with an end hole in each, where as the present invention teaches the use of side holes. The '638 shows is an angled hole ventricular catheter designed for extended impartment in the brain, whereas the present invention does not use angled holes and is not intended for extended impartment in the brain. U.S. Pat. No. 4,755,176 teaches a catheter with side hole in one of two lumens, whereas the present invention is a single lumen device.
The art prior to the inventor's other disclosures suffers from several significant shortcomings. These include difficulty forming a proximal “plug” before too much distal Onyx prevents a subsequent ejective distal “push”, too much reflux of Onyx along the micro-catheter, approaching a normal branch artery, necessitating aborting that injection for safety concerns. Other shortcomings include slow plug formation, and the need for longer procedures necessitating longer fluoroscopic times and higher radiation doses.
The prior art also fails to adequately address the fact that during the initial “plug” injection(s) of Onyx 34 (after lacing the micro-catheter with dimethyl sulfoxide) are off target. Consequently some of the plug material ends up in the distal most tip of the micro-catheter (beyond the side hole). Additionally, typically the plugging material, such Onyx 34, when in contact with blood that is not moving will then start to solidify in the tip of the micro-catheter, and can obstruct it. An obstructed, distal penetration of the lesion being treated with the embolics agent is no longer possible
An improved liquid embolic agent delivery system is required to ameliorate said difficulties. It appears that the present invention is an excellent alternative to existing embolic agent delivery systems because it allows said ameliorations. In particular, it is easier to use than existing delivery systems, allows faster plug formation, and requires less procedural time and X-ray/radiation dosage; it is also more consistently effective.
Said micro-catheters and embolic agents often require creating a plug at the distal-most portion of said micro-catheters in order to facilitate optimal subsequent embolic penetration. Typically, treatments are suboptimal when there is difficulty forming a “plug”. Said difficulties can result in liquid embolic failure to penetrate the target area, such as a fistula's nidus.